1. Field of the Invention
This invention is generally directed to block and tackle arrangements for connecting the hooks of a shed forming device of a weaving loom with the heddle or harness threads.
2. History of the Related Art
Shed forming devices have been known to exist for a long time, comprising knives moving in opposition in a reciprocating movement to cooperate with the hooks for controlling heddles or harness threads in a weaving loom. The hooks are connected by a cord which passes around the first pulley of a block and tackle of which the second pulley is surrounded by a cord having one of the ends secured to the frame, while the other end is associated with at least one heddle. Such a device is described in particular in Swiss Pat. No. CH-367 452.
Shed forming devices of this type allow a certain opening of the shed which is of the order of 100 mm. If it is desired to increase the magnitude of the shed, for example for making carpets or other fabrics, the free end of the cord mentioned above is attached to a fork joint in which is mounted an idle pulley guiding a funicular element of which one of the ends is fixed with respect to the loom frame, while its free end is associated with at least one heddle.
It will readily be appreciated that the block and tackle with two pulleys and the idle pulley must be offset longitudinally so as not to interfere. In the same way, it is necessary to guide them longitudinally to avoid their collision with the corresponding members of adjacent systems.
In view of these factors shed forming devices are complex to produce since it is necessary to provide the above-mentioned guides as well as the crosspieces which constitutes the points of anchoring of the cords and funicular elements.
The improvements forming the subject matter of the present invention aim at overcoming these drawbacks and at enabling a simple shed forming device to be produced which is of small dimensions and of economical cost.